1. Field of the Invention
The present invention relates to a semi-transmissive liquid crystal display device and more particularly to the configuration of optical control layers provided on the front side of a display panel.
2. Description of the Related Art
In recent years, a semi-transmissive liquid crystal display device has been used for applications, such as a PDA (personal digital assistant), a portable telephone and a portable electronic device, in which suppressed power consumption and improved display performance are required. For such applications, the semi-transmissive liquid crystal display device is preferred which utilizes external light such as sunlight or illumination light at daytime or under bright indoor environment and further utilizes backlight at nighttime or under dark indoor environment.
However, when the semi-transmissive liquid crystal display device is used mainly in a transmissive mode using backlight at nighttime, the device occasionally causes a phenomenon in which the viewing angle characteristics of the device deteriorates depending on the viewing angle in relation to a display screen. In addition, when the semi-transmissive liquid crystal display device is used mainly in a reflective mode using sunlight at daytime, the device causes a phenomenon in which parallel rays of sunlight incident on the liquid crystal display device are diffracted within the device to produce rainbow-colored and stripe-shaped light or radial light. In order to prevent those phenomena, the surface of display device is, in some cases, processed to convert incident light to scattered light. The conversion of incident light is generally performed by forming an anti-glare (AG) layer on the surface of the display device. However, the surface of display device thus processed causes sunlight to be scattered backward off the display device (hereinafter, referred to as backward scattering), i.e., scattered toward a viewer, resulting in the phenomenon in which the entire screen cannot be viewed depending on the viewing angle because of white representation on the entire screen.